Motor drive for medical syringes



FRE, 28, i195@ G. B. GLASS MOTOR DRIVE RoR MEDICAL SYRINGES Feb. 2, E950v G. B. GLASS 2,498,672

MOTOR DRIVE FOR MEDICAL. SYRINGES Filed May 26, 1947 3 Sheets-Sheet 2Feb. 28, 1950 G. B. GLASS MoToR DRIVE FOR MEDICAL SYRINGES 3Sheets-Sheet 3 Filed May 26, 1947 Patented Feb. 28, 1950 MOTOR DRIVE FORMEDICAL SYRINGES George Bronislaw Glass, New York, N. Y., assignor toAntonna. S. Glass, New York, N. Y.

Application May 26, 1947, Serial No. 750,481

This invention relates to improvements in automatic means for operatingmedical or hypodermie syringes and to a combination of such means withone or more medical or hypodermic syringes of standard size and style.

Medical syringes at present in use are generally hand-operated and thislimits the use and facility with which an injection oi long duration maybe administered. Therefore, for such injections use is made of flasksprovided with drip devices from which the fluid drips by gravity, butthese flasks cannot be used for injections of small amounts of drugsover extended periods of time. There is, nevertheless, frequent need foran injection device which can administer small amounts of drugs overcertain extended periods of time, such as in the case of intravenouslyadministered anesthetic drugs during operation, or the injection of somecontrasting media preparatory to the taking of X-ray photographs, asWell as for the administration of small amounts of drugs that arerapidly destroyed or eliminated from the body and which neverthelessshould be maintained at a given concentration in the blood for adeiinite length of time.

, The present invention provides a means ofthis kind and supplies anautomatic device which, save for the preliminary insertion of the needleinto the body of the patient, requires no hand operation and is not heldby the administrator or physician. To my knowledge there has notheretofore been any satisfactory commercial instrument of this kind onthe market.

According to the present invention l' provide an apparatus adapted tohold the 'body of a medical syringe in a stable position, combined withmeans adapted to impart a desired axial movement at a predetermined slowspeed to the plunger of the syringe, whereby solutions or dispersions ofdrugs or other medicaments may be automaticallyv injected into the bodyof a patient at a controlled and constant rate.

According to the invention I provide means of the character abovereferred to which are adapted for use with standard type medicalsyringes. In one embodiment of my invention the apparatus comprisesclamps for holding the barrel or casing of the syringe, supports towhich the clamps are secured, and a plunger rod provided With means forengaging the piston of the syringe, a screw-threaded drive shaftassociated with the conventional drive shaft of an electric or similarmotor, a connecting member connecting the screw-threaded drive shaft tothe plunger rod and means for putting the connecting mem- 6 Claims. (C1.12S- 218) ber into and out of operative relationship with` thescrew-threaded drive shaft.' By using al screw-threaded drive shaft offine pitch, and electric or other motors of vfractional horse-power,with or-vvithout variable gear transmissions or other such controls,extremely slow drug injections can be automatically administered atsubstantially any desired rate. y

The invention will be better understood from the following descriptionof the particular em- T bodiments of it which are illustrated in theacsyringes and yit shows the relative arrangement of the parts of thedevice and of the syringe at the beginning of an injection; l*

Fig. 2 is a side elevation of the apparatus illustrated in Fig. 1showing the relative position of the parts at the conclusion of aninjection.

. Fig. 3 shows a side'v'iew of the apparatus as set up for use with arelatively small medical syringe and shows the use of agovernor-controlled electric motor; v

Fig. 4 is a top plan view of a similar apparatus to that illustratedinFig. 3;

Fig; 5 is a part sectional view of the interchangeable supporting clamptaken along the line 5 5 of Fig. 3;

Fig. 6 is a frontview of a supporting clamp for a large size syringev'as used in the apparatus illustrated in Fig.1;

Fig. 7 is a fragmentary view of a modiiied form of the connecting memberconnecting the plunger rod of the' driving mechanism to the driveshaft;-

Fig. 8 is a front `view of the modied device illustrated inFig. 7; g

Fig. 9 is a side view of the same member showing in more detail itsassociation with theplunger rod and driveshaft; Fig. 10 isa sideelevation of a further modification of the apparatus shown incombination with an electric motor, a variable gear transmission andalarge size medical syringe in the positions assumed at the beginningiofan injection.

Fig. 11 is a top plan View vof the apparatus illustrated in Fig.10,"without the speed-changing mechanism, butwith a rheostat and withthe propelling mechanism inthe position it assumes at the end 'of aninjection.l g

Fig. 12 is a front view of the propelling and connecting member employedin the modification illustrated inFigs. `10 and 11;

Fig. 13 is a rear View of the part illustrated in Fig. 12;

Fig. 14 is a front view of a supporting arm and clamp as used in themodiiication illustrated in Figs. and 11 for clamping the syringe casingin place.

Referring first to the modification illustrated in Figs. 1 to 6, theapparatus comprises a base plate 'I provided with slots 8 and 8a runninginwardly from each end, and which act as runways within which, at thefront end, a clamp I, together with its supporting member 3, may bemoved .to accommodate syringes of diierent lengths, 'while the rear slot8a is similarly employed to allow for the longitudinal positioning ofthe electric motor 32, in accordance with the needs governed by the sizeof the syringe employed and the predetermined length of travel of thesyringe piston.

Each of the clamp members, of which two are shown for securing thesyringe barrel creasing. comprises a splitring I secured to an arm2-which in turn is received in a correspondingly sized recess providedin a supporting member 3 and secured therein by means of` screw 5. Therear of the two clamps l has a supporting block 4 which is rigidlysecured to the base 'I., while the front clamp has its supporting block3 attached to extension 3a, the supporting block 3 and the extension 3cextending below the bottom oi the base plate I andbeing ofA greaterwidth than the slot 8 so as to be slidably movable along the slot 8y andto be secured therealong in. any desired position byl means of screw 9.

" 'Ihe barrel or casing Iiv of a hypodermic syringev with its ared endof yoke piece 6a. is received in the two clamps I. the size of thelatter and their position relative to each other along the base plate 'lbeing selected to accommodate the requirements for a balanced holding ofthe syringe 6. The piston II. oithe syringe with Aits customarilyiianged or enlarged end IIa is.` supported in operation by twol grippingmembers Il secured by a cross-,bar I6 (Fig. 4) and screw I5 to plate I2which is hinged by hinge. I3 to the plunger rod head I0 securedto theplunger rod I8 of the propelling mechanism. .The plate I2 is slotted asat I4 to allow adjustment therealong of the grips I1.

The plunger rod I8 is provided alongy its upper surface with alongitudinally extending slot I9 as shown in Fig. 4 and is provided witha longitudinally extending bore 90 k(Fig.y 1) disposed throughout itswhole length andin which a screwthreaded drive shaft 24 is, free totravel. The plunger rod I8 is. prevented from rotating during itsforward movement by means of a pin 22 riding in the channel I9; the pin22 isscrewed into the top of bearing 20 through which the plunger rod I8passes, the bearing 20 being rigidly secured to the base plate 'I bysupport 2 I.

To the rear of the plunger rod I-B an integral connecting member i` isprovided, which in Figs.

l to 4, takes the form of acasing 23 provided in its lower hal-f with ascrew-.threaded segment 2-5 that meshes with the screw-threaded driveshaft 24; the upper halfy of the. casing 23 is prosecured tov ascrew-threaded shaft. 21 associated 4 housing 32 which by means of screw34 and nut 36 is adjustably secured along the slot 8a to the base plate'I.

In Figs. 3 and 4 a governor-controlled electric motor 87 is shown and inthese two figures electric leads 36, plug 31, socket 38 and switch 39-The clamps holding the syringe can be replaced by releasing. the screw5' and withdrawing arm 2 with the attached clamp I and replacing it withanother clamp of the desired size. Thus in Fig. 6 a larger clamp isillustrated as can be used for the large syringes 4illustrated indrawings of Figs. 1 and 2.

In operation the modication illustrated .in Figs. 1 to 6. functions asfollows; The syringe. 6 with its piston II is mounted in the clamps. I',a hypodermic Yneedle attached to outlet tubing 4I of the syringe is.inserted in the body of the patient and the end of the syringe pistonII. is secured in the grip I-'I,`this grip device being shown ininoperative positionin Fig. 3 and in operative contact with the syringepiston II in Figs. l and 2. The speed of injection is deter? mined andthe. speed-of the electric motor 3l established accordingly, the screw2l of the connecting member 23 is turned tobring the screwthreadedportion 26 intomesh-contact ywith-the drive shaft 24, the switch 39 isturned on and the injection allowed to. proceed. By choosing ascrew-thread of fine pitch' for the drive shaft 241 and if necessaryadditionally adjusting the speed of rotation of the drive shaft. as byinterposing a reducing gear mechanism and the like, an extremely slowinjection over an extended period of` time canbe maintained. It isunnecessary for the syringe to be held in the hand at any time.Furthermore theapparatus is designed for use with syringes of thestandard kind and which arereadily purchased in the market.

When the piston II has completed its full stroke, or whenever it isdesired to interrupt the injection, the motor isV switched off, thegrips I'I released from engagement with the head of the syringe pistonbyiznullingv on knob I5 to rotate the plate I2 about hinge i3, so thatthis attachment assumes the position shown in Fig. 3. Then screw 28 isturned counter-clockwise to raise the threaded segment 26 of theconnecting member 23 from out ofl meshing` engagement with the threadeddrive shaft 2,4. The bore provided in the plunger rod I8 being ofsomewhat larger diameter than the drive shaft 24 .and a certain amountof play also. existing inthe bearing 20, the operator can disengage the`lower part 2,5 of the connecting member 23frommeshing engagement withthe drive shaft 24, by simply exerting a slight downward pressure on theknob 28 so that the plunger rod is slightiyl bent out of alignment withthe drive shaft24. The entire plunger rod with its front and rearattachments isn then readily withdrawn to thep'rear or initial positionby hand andthe apparatus is again ready for use in the next injection.V

In the modification illustrated in Figs. 10r` and' 14 the base plate Iis slotted only at its rear end 33' for relativepositioning of theyelectric motor 1I. At its forwardfendv the clamps 52 are se-v cured by4arms 53,`V pin 5d, boss 58 `and screw 59 around a bar I which issupported-by 'standards 49 and 50 that are rigidly secured to the'rbaseplate 1. The front clamp 52 is adjustable along the bar 5I, which maycarry a scale 6I, whereas the rear clamp 52 is not adjustable alongthebar 5I but is secured in one position by flanges 80 provided on thebar 5I. The clamps 52 may be turned somewhat along vthe bar 5I foradjustment in alignment with they syringe barrel by releasing nut 59. Bylongitudinal adjustment of the front clamp member 52, syringe casings 6of varying lengths can be properly accommodated. To the rear of thestandard 50, drive yshaft 24 is journalled in bushingsl 64, onebeingfsecured to the standard 50 and the other to a rearstandard 63.Guide rails 8| also secured to standards' 50 and 63 are provided aboveand laterally of the screw-threaded drive shaft 24 for thefguidingcontrol during travel of a modifiedk connecting and propelling devicewhich is illustrated in some detail in Figs. 12 and 13.

The connecting and propelling device illustrated in Figs. to 13comprises an internally screwthreaded member 13 meshing with the driveshaft 24. The member 13 is in the form of a split nut, each sector ofwhich extends to form cross-arms 14 having rectangular extendingprojections pivotally secured to a rectangular bar 18 by pinion 16, saidarms 14 being continuously pressed apart by coil spring 11 and adaptedto be brought together by manual pressure of the fingers in the recessedportion 15 to compress the spring 11 and to disengage the split nutportion 13 from engagement with the drive shaft 24.

The rectangular bar 18 at its baselis secured to or formed with atransverse segment 19 having bore cuffs 80 through whichthe guide rods8| continuously pass. The rectangular bar 18 is provided with arelatively narrow vertical ,propelling bar 82 depressed at its front endand provided in its upper part with a small convexity 83 adapted toengage with the conventional concavity in the head of the syringepiston'I I. The propelling bar 82 is provided with two grasps 84 mountedon two parallel segments 85, whose relative positions are adjustable tothe size of the piston II of the syringe with which they engage. Theadjustment of the segments 85 is leffected by suitable release of thescrew 86.

The drive shaft 24 has a non-threaded extension 65 secured to the driveshaft 61 of a motor 58 by means of screw 56 (Fig. 11) avariable geartransmission 18 with adjustable switch 89 can be interposed between themotor 68 and the drive shaft extension 65, if desired, as-shown in Fig.

10. Electric motor 58 is contained in the housing 1I and adjustablysecured in the slot 33 of the base plate 1 by means of a screw 12. InFig. 11, 88 represents a rheostat which can be employed for regulatingthe speed'ofthe electric motor instead of the variable gear transmissionrepresented by 18 in Fig. 10.

Fig. 14 illustrates in greater detail the style of clamp used to holdthe piston barrel 8 in the modification shown in Fig. 10. The relativeposition of the two arms 53 may be adjusted by means of a wing nut 51 onthe screw 55 in counter-action lto spring 56. `Rubber grips 82 areprovided for contact with the syringe casing.

In operation, the modification illustrated in Figs. 10 to 14 is similarto that described in ref,- erence to the modification illustrated inFigs. 1 to 6. The connecting member 13"tra`vels on the drive shaft 24'and propelsthe member 18 along the guide rails 8| to cause thepropelling bar 82 toc'ause the pistonv II to move axially forward intothe syringe casing 8.

The normal procedure is to switch off the motor at the end of itsstroke, disengage the grips 84 from the syringe piston by releasingscrew 88, disengage connecting member 13 from drive shaft 24 by nger andthumb pressure on recessed portions 15 of the connecting member andmanually withdraw `the whole connecting and propelling member 13 back toits initial or rear position along the drive shaft 24. The guide rods 8|constantly maintain the Vconnecting and propelling member 13 in thedesired upright and stable relationship to the drive shaft 24.

A modification of a further suitable vconnecting member associating thedrive shaft 24 with the plunger rod I8 is illustrated in Figs. 7 to 9.Inv

this modification the connecting device comprises a split,internally-'threaded nut 42 adapted to encompass and mesh with thescrew-threaded drive shaft 24, each section 42 being integral witharcuate pincer-like members 43 connected at their lower endsby spring 48and pivoted to rod 46 by pinion 44; rod 48 bears against'extension 41secured to the end of the plunger rod I8 (Fig. 9). The arms 43 of thepincer arrangement extend upwardly to conclude in handlesor grips 45.The` sections d2 lie normally in juxtaposition in mesh with the threadeddrive shaft 24 and this connecting member canbe released at will fromengagement with the drive shaft 24 by squeezing the grips together asshown in Fig. 8 to disengage sections 42 from drive shaft 24 and toallow the entire connecting unit to be puolllcal back manually togetherwith the plunger ro The motor preferably used is an electric motor offractional horse-power such as a synchronous timing motor of a permanentmagnet type and having a constant rate of revolution and provided with agear-speed'reducingunit adapted to reduce the rate of revolutions fromone to ten R. P. M. Other motors such as capacitor motors, shade polemotors, series-wound fractional horse-power motors may be employed.

Conventional electrical speed-varying devices, such as rheostats andgovernor controls can be used or conventional reducing gear mechanismmay be interposed between the electric motor and the drive shaft of theapparatus. Obviously it is possible to substitute one kind of motor foranother as desired. and, in addition, a series of similar devices may beerected on one base and driven simultaneously from one motor or operatedindividually from separate motors. All connecting devices and clampingarrangements shown in eachof the foregoing illustrated modifications canbe interchanged as desired.

By way of illustration, use can be made of an electric motor arranged totransmit eight revolutions per minute to the drive shaft, the latterbeing threaded to the extent of 20 threads per inch to result in aforward -movement of the syringe plunger at a constant speed of about 1cm. per minute. The piston of a 5 cc. syringe has an approximate lengthof 4 cm. and at this rate it completes its full stroke in four minutes,whereas the piston of a cc. syringe, which has a length of about 11 cm.,has a time of travel of 11 minutes at this rate. This is fairly goodrange of speed for a slowly performed intravenous injection but if adrip injection is to be done and is to extend over a period of severalhours, amotor having a range of speed of four to leight revolutions perhour may be used. With such. a motor thel above kind 'of' syringes willbe emptied in from 4 to 22 hours, depending` on the' size ofthe-,syringe used.

Various modificationsl may be introduced -asf will be obvious to thoseskilled: in the art to controlthe rate and extent of injectionsperformed by this` device. The advantage of having fully automaticinjection mechanism of this kindis very considerable and is of greatutility to the medical profession.

Since many variants may be obviously intro'- duced into the features ofthis invention without departing from.v the spirit and scope thereof, itis to be understoodl that the modifications shown in the. 'accompanyingdrawings are to bel interpreted'. in an illustrative rather than in alimit.`

ing sense. v

1. In a device for automatically operatingpa medical. syringe, whichsyringe comprisesA a syringe barrel and piston, a base, means forrigidly holding the syringe barrelv secured to a stationary portion ofthe device,` a plunger rod head, means for releasably-engaging said headwith the syringe piston, a plunger: rod attached to said plunger rodhead, a bearing for said plunger rod, means fory preventing rotation ofsaid plungerrod during axialv travel thereof, a motor, a housing for amotor secured to said base,` an axially disposed screw-threaded driveshaft parallel to said plunger rod and journalled to said motor, meansvfor changing. the rate of rotation of the drive shaft, a connectingmember operatively connecting saidplungermd and said screwthreaded,driveV shaft and. movable co-axially but not rotatably with the latter,said connecting membercomprising a casing securedltorthe rear end of theplunger rod,. an internally.l screwthreaded.' split; nut surrounding andmeshing withv the-screw-threadedidrive shafthousedinsa-id casing, andmeans for: disengagingv saidsplit nut from meshingl engagement with'said screwthreaded driveshaft.. l

- 2.v In a device: for automaticallyA operating a medical.- syringe,which; syringe: comprisesv a syringe barrel, and. piston; ay base',`meansy for rigidly holding` the syringe barrel secured t'of astationaryportion of= the dev-ica.. a# propelling membenmeansa for releasablyYengaging said propelling; member with the syringe: piston. guide means.for: saidi propelling, member securedtof a pellingA member and said'drive shaft andmovable co..-ax\iallybutnot rotatably with the.- latter,said connecting member comprising a.- casing secured toYthe:propelling', member, aninternally threaded split nut` surrounding',and meshing.- with the screw-threaded drive-shaft and. attached to saidcasing, andfmeans for disengagingl said splitr nut from. meshingengagement with saidscrewthreaded drivefshaft.

3. In al device for automatically operating a medical syringe, which:syringel comprises a syringe barrel and piston; a base; clampmem-` bersfor. rigidly. hnldingthel syringe barrelI tofsaid base, means foradjusting the relative positions ofv said clamp members according to thesize of the syringe,` afplunger `rod head, releasable grasps secured tosaid lhead operatively. engaging the syringe piston, a plunger rodconnected to said plunger rod head andI having; an externallongitudinally extending slot, a `tubular passageway in saidy plungerrod,` a plunger rod bearing secured' tosaid "base in which the plungerrod is free to move'axially, a pin mounted in said bearing' and. ridingin said slot to prevent rotational movement. of the plunger rod duringaxial travel thereof, an --a-xially extending screw-threaded drive shaftdisposed to ride rotatably in part within. the passageway i-n theplunger rod, a motor, a housing for-,said motor secured to said base,guide means for moving said housing axially along-v saidy base, meansYconnecting said screwthreaded drive shaft to said motor, means forchanging the rate of rotation of the drive shaft, and.af'connecting'member for releasable engagement of said plunger rod withsaid screwthreaded drive shaft .and movable co-axially lbutnot'rotatably with the latter, said connecting member comprising.- acasing, secured to, the plunger rod, an internally-threaded split nutdisposed around andadapted to mesh with said screw-threaded drive shaft,and a screw passing through said casi-ng and secured to one section ofsaid split nut.` I

4. In a device for automatically operating a medical' syringe, whichsyringe comprises a :syringe barrel and piston, a base, clamp membersfor'rigidly holding the syringebarrel to said base, `means for adjustingthe relative positions of :said clamp members according to the size ofthe syringe, a plunger rod head, releasable grasps .secured to saidheadoperatively engaging the .syringe piston, a plu-nger rod connectedto said plunger rod head and having an external longitudinally'extending slot, a tubular passageway in saidplunger rod, a. plunger rodbearing secured to said .base in which the plunger rod is free tov moveaxially, a pin mounted in said bear- .ing and riding in said slot toprevent rotational :movement of the plunger rodduring axial travelthereof, van axially extending screw-threaded drive -shaft'l disposed toride rotatably in part within the passageway of the plunger rod, amotor, a housingv for said motor secured to said base, guidey means formoving said housing axially along said base, means connecting saidscrewthreaded driveshaft to said motor, means for Achanging the rate ofrotation of the drive shaft, :anda'` connecting member for releasableengage- :ment of said plunger rod 'with said screwthreaded drive shaftand movable co-axially but not rotatably withv the latter, saidconnecting member comprisinga spring-actuated and internally-threadedsplit nut vmeshing with said :screw-threaded drive shaft, extensions onthe split nut portions forming cross arms journalled 'to said plungerrod, and means for manually releasing 'sai'dfsplit'nut from engagementwith said .screw-threaded drive shaft.

5. In a device for automatically operating a med-ical syringe, which'syringe .comprises a barrel and a piston, a base, clamp members forrigidly holding the syringe barrel to said base, means .for adjustingthe relative positions of said clamp :members according to the size ofthe syringe, a propelling member, Areleasable grasps secured to saidpropelling member operatively engaging the 4.syringe piston,longitudinally-extending guide means for said propelling member securedto said T5 ibase for,.:preventing rotation of said propelling memberduring axial travel thereof, a motor, a housing for said motor securedto said base, an axially disposed screw-threaded drive shaft journalledto said motor, bearings for said drive shaft secured to said base, meansfor changing the rate of rotation of the screw-threaded drive shaft anda connecting member for securing releasable engagement of saidpropelling member with said screw-threaded drive shaft and movablecoaxially but not rotatably with the latter, said connecting membercomprising a casing securedv secured to said propelling memberoperatively engaging the syringe piston, longitudinally extending guidemeans for said propelling member secured to said base for preventingrotation of said propelling member during axial travel thereof, a motor,a housing for said motor secured to said base, an axially disposedscrew-threaded drive shaft journalled to said motor, bearings for saiddrive shaft secured to the base, means for changing the rate of rotationof the screwthreaded drive shaft, and a connecting member for releasableengagement of said propelling member and said screw-threaded drive shaftand movable co-axially but not rotatably with the latter, saidconnecting member comprising a spring-actuated and internally-threadedsplit nut meshing with said screw-threaded drive shaft, extensions onthe split nut portions forming cross arms journalled to said propellingmember, and means for manually releasing said split nut from engagementwith said screw-threaded drive shaft. y

GEORGE BRONISLAW GLASS.

REFERENCES CITED UNITED STATES PATENTS Name Date Campkin Jan. 22, 1935Number

